Hydraulic brake system



Aug 2, 1932- J. w. WHITE V1,869,452

HYDRAULIC BRAKE SYSTEM Filed Aug. 10 1925 IIIIIII Patented Aug. 2, 1932 JOHN WILLIAM WHITE, OF BUFFALO,

NEW YORK HYDRAULIC :BRAKE SYSTEM Application filed August 10, 1925.

r1`his inventionrelates to an improvement in motor vehicles, and more particularly to a pedal mechanism for a hydraulic brake installation.

e Prior to this invention it hasbeen the universal practice commercially to provide a cylinder in the fluid circuit vof a hydraulic brake installation and to provide a pedal connected mechanically by means of links and levers lo with the piston of the cylinder. d I

' rlhe primary object of this invention is to provide in place of the cylinder and mechanical connections mentioned simple hydraulic means for actuating the hydraulic brakes.`

A further objectof this invention is to provide a pedal which comprises a booster cylinder located in the fluid circuit of the hydraulic brake installation and having a piston the depressionof which eXerts pressure 2.0 directly upon the fluid of the circuit and so operates the brakes. n

Other objects of this invention will appear from a consideration of the following specilication taken in connection with the accompanying drawing, which forms a part thereof, and in which Fig. 1 is a longitudinal section on an enlarged scale of the mechanism with the piston completely depressed;

with the piston completely raised intov the normal position; Y

Fig. 3 is a bottomfplan view of the mechanism; and i 35 Fig. 4 is a cross sectional view along the line 4-4 of Fig. 1.

Referring now to the drawing it will be noted that the numeral 14 designates a casing and 14 a piston having a rod v15' at the 4 -upper end of which is mounted a pedal 16. V The numeral 24 is used to designate a portion of the circuit through which fluid passes to the brakes and into which is 'introduced the T-tap 25. The ends of the tap are secure 45 to the ends of the circuit 24 .by means o lnions 26 so that the tap circuit., The central portion-27 of the tap is threaded into an externally and .internally threaded nut 28, which is in turn threaded 0 into the lower end of the casing 14. Thus 'upper portion Fig. 2 1s a similar view on a smaller sca-le .p

forms a part of the Serial No. 49,391.

the chamber 29 of the casing is an element of the circuit 24 and is also filled with fluid. At the upper end of the casing 14 is formed an annular seat 30, on which rests the end of a sleeve 31. Set screws 32 secure the sleeve 55 31 in position.` The rod 15 is preferably noncircular, here shown as hexagonal, and the of the sleeve has a similar contour, thus preventing the rod from rotating in the sleeve. Since the sleeve 3l is fixed 60 in the casing by the set screws 32 the rod and its plate 1 6 cannot turn 1n the casing 14. This is particularly important when the oval plate 16 illustrated in the drawing is used. At a' recess 33 in the upper end of the sleeve is in- 65 troduced a gasket 34 held in place by an annular disc 35 and a split ring 36. 4*The gasket acts` to prevent entry of air into the cylinder or casing.

Secured to vthe inner end ofthe rod 15 is 70 a metal ring', which has a free movement in the casing 14 and prevents any tilting of the rod 15. Mounted for reciprocation within the casing below the rod is thel piston 14 ycomprising a disc 39- and a rubber cup' 75 d shaped member 40 joined to the disk at the center by a rivet 41.

l llt'ha's been found that there is a tendency for the cup 40 to expand at the base under ressure and consequently cause binding between the piston and the casing. To overcome this and at the same time not interfere rwith the lfunction of the lip 42 of the rubber cup the disc 39 is provided with an annular flange 43,- which confines the base of the cup and prevents its expansion laterally under pressure. The lip 42, however, is free to4 bear against the walls of the casing and seal 29. The purpose of this construction will be pointed out below in connection with the statement `of operation.

The foot plate 16 has an integral periph- I eral flange 44- which positions a resilient pad the chamber d 45. At the base of the casing 14 is provided f an opening 46 normally closed by the screw 95 47,y which opening serves as a bleed valve tp ermit the escape of air when the casing is eing filled with liquid.

The normal position ofthe parts of the4 mechanism is illustrated in Fig. 2, and iit e its normal condition and recense will be understood that the casing lll below the piston lll is filled with fluid and is in free direct open communication With the Circuit 2st. Obviously by applying pressure to the plate 16 the piston is 'depressed forcing the fluid from the chamber 29 into the circuit, and thus exerting pressure upon the brakes in the usual manner. lVhen `the pressure is released, the fluid Will tend to resume vill act upon the piston rod forcing it to rise With the piston to its original position shown in Tfigure 2.

*Under certain conditions the pedal may rise slowly and there a tendency on the Y part of some operators to lift the pedal by placing the toe under the plate. Obviously the piston should only risc as fast as the fluid is returned and any attempt to lift it bodily is liable to admit air into the circuit vwhich would affect deleteriously its functionsb For this reason in the mechanically operated pedal mechanism referred to above as in general use there is provided a loose linl connection outside the cylinder which permits this positive lifting of the pedal Without damage. The provision of the piston separate from and independent of the piston rod l5 functions as a loose link connection for this reason, the connection, however, being inside the cylinder. ',lhe piston can rise only as fast as the fluid is returned, but the pedal can be lifted positively if desired Without in any way affecting the operation of the cup.

The position of the pedal when pressure is relieved is a-positive indication of the amount of iuid in the circuit, so that the operator is advised at all times of its condition. rlhis indicator function is far more delicate than that of the old commercial type of pedal, because in the latter it is necessar7 to provide a plurality of links and levers in order to attain the proper travel for the piston in the cylinder, Whereas in this mechanism the full travel is provided at the pedal.

While one embodiment of this invention has been shown and described, applicant is not limited thereto, since it is obvious that other embodiments can be made Without departing from the spirit and scope of rthis invention as set forth in the following V2 ln a hydraulic brake system, a pressure inducing instrumentality including, a cylinder, a piston rod in said cylinder, a substantially cup-shaped flexible piston in advance and independent of said rod, a disc also .in-

dependent ofthe rod and interposed between the end of the rod and cup-shaped member, said disc having an annular flange surrounding the b-ase portion of the Cupshaped member for supportingthe latter, and pedal secured to the outer end of said rod for actuating the latter.

3., ln a hydraulic brake system, a pressure inducing instrumentality including, a cylinder, a piston red extending Within the cylinder, a ring carried by the inner end of said rod and slidably engaging the Walls of the cylinder for restricting movement of the rod in a rectilinear path, al substantially cupshaped flexible piston arranged Within the cylinder in advance and independent of the rod, a disc interposed between the end of the rod and cup-shaped member and having an annular flange surrounding the cup-shaped member for supporting the latter and means for actuating the rod and piston.

et. ln a hydraulic brake system, a pressure inducing instrumentality including, a cylinder, a piston rod in said cylinder, an inverted substantially cup-shaped vflexible piston in advance and independent of the rod, a disc 4interposed between the end of the rod and cup-shaped member, said disc slidably engaging the Walls of the cylinder and secured to the base portion of the cup-shaped inember, and an annular flange upon said disc surrounding a portion of the cup-shaped member for supporting the latter.

ln testimony whereof l have aiiixed my signature.

JOHN VVILLAIVI "WHITE 

